Many aspects of modern society require the availability of modern communication systems through which to communicate data. A communication system is formed, at a minimum, of a sending station and a receiving station. The sending and receiving stations are interconnected by way of a communication channel. Data that is to be communicated is sourced, or otherwise originated at, the sending station. The data is sent upon the communication channel to the receiving station. the receiving station operates to receive the data communicated upon the communication channel and to recover the informational content thereof.
While many different types of communication systems have been developed and deployed, telephonic communication systems are perhaps the most pervasive and popularly utilized communication systems. Telephonic communication systems include telephonic networks through which telephonic communications are effectuated. Telephonic stations are connected, in communication connectivity, with a telephonic network. And, the telephonic stations form originating and terminating stations between which users communicate telephonically. Telephonic communication of both voice data and non-voice data is provided by various types of telephonic communication systems.
Telephonic communications are effectuable, for instance, between a calling party that originates a call at an originating telephonic station and personnel located at a service center forming a public safety answering point. The service centers are identified by shortened dialing codes forming universal dialing codes, at least throughout selected geographical areas. For instance, in the United States, the three-digit telephone number 9-1-1 forms a universal emergency number, used by a calling party to call an emergency service center forming a public safety answering point. In other geographical areas, analogous dialing numbers are used to identify analogous service centers.
That is to say, the 9-1-1, or other analogous, dialing code forms a nationwide telephone number in the United States, usable by any calling party to place a call to the emergency service center forming the public safety answering point. A large number of public safety answering points are positioned throughout the nationwide, geographical area. Each of the public safety answering points is identified by the same universal dialing code. Call routing must route the call to an appropriate service center. Typically, the appropriate service center is a service center positioned in close proximity to the location from which the call is placed.
The National Emergency Numbering Association (NENA) is involved in the planning and implementation of a universal, 9-1-1 telephone number system in the United Sates. Such universal telephone number systems are embodied in existing telephonic communication systems. The NENA also defines 9-1-1 technical issues and recommends solutions to the technical issues, maintains a public safety answering point registry containing contact information relating to the public safety answering points, and maintains links to public safety related organizations and communication centers.
The universal, 9-1-1 emergency telephone number systems generally include, or make use of, several network elements. Such network elements include, for instance, end office switches, E-911 tandem switches, and public safety answering point end nodes.
When a call is placed by a calling party at a calling station, the call is connected to an end office. The end office, in turn, routes the call to a selected one of a plurality of E-911 tandem switches that serves an area. The E-911 tandem switches operate, amongst things, to select and to hand off the call to a selected one of a plurality of public safety answering points that service the area. Thereby, a 911, or other analogous, call originating at an originating calling station, i.e., an end user telephone, is routed by way of a local end office to an appropriate E-911 tandem switch. Signaling is performed pursuant to the call routing. In some networks, multi-frequency (MF) signaling is utilized; in some other networks SS7 ISUP signaling is performed.
Conventionally, the selection of the selected public safety answering point to which to deliver the call is made by accessing an on-board selective routing data base embodied at each of the E-911 tandem switches. The data base includes a listing of the originating telephone number, i.e., the dialing number associated with the originating station and the identity of a public safety answering point associated with the originating telephone number. There is, e.g., a single public safety answering point associated with each telephone number. The identity of the public safety answering point is derived from an emergency services number (ESN) of the public safety answering point. The tandem switch uses the ascertained emergency services number to select the appropriate public safety answering point and to transfer the call there. Alternate routing provisions are sometimes also provided to permit routing of the call to a substitute public safety answering point should all circuits for the primary public safety answering point be in use or blocked.
The information used to route the call to the selected public safety answering point is distributed throughout the network of the telephonic communication system. That is to say, the information is stored at each of the E-911 tandem switches. When the information needs to be updated, such as when the ESN of a PSAP changes, potentially a large number of data bases must be correspondingly updated. Updating of the large number of data bases is potentially an arduous and costly task.
Additionally, as the emergency 9-1-1 dialing code might be entered by a mobile station, the selected public safety answering point to which the call should be routed is susceptible to change, depending upon the location at which the mobile station is positioned when the call is placed. The existing emergency system is predicated upon fixed-positioned telephonic stations. Additional steps must be undertaken to determine the selected public safety answering point to which to route the call placed by a mobile station.
If a manner could be provided by which to overcome these problems associated with conventional emergency dialing services in a telephonic communication system, improved call routing would be possible.
It is in light of this background information related to routing calls in a telephonic communication system that the significant improvements of the present invention have evolved.